Intelligence officials tell NBC News four of the five Americans working at the natural gas complex survived: two escaped and two more are being held. The kidnappers are saying they will exchange the US hostages for two high-profile terror suspects currently in US custody. NBC's Stephanie Gosk reports.

By Jim Miklaszewski and Tracy Connor, NBC News

One American was killed and two escaped unharmed from a natural gas complex in Algeria that was stormed by armed militants, U.S. officials said Friday. The fate of two others was unclear.

The officials said there was a total of five Americans at the In Amenas plant in eastern Algeria when the attackers seized dozens of hostages on Wednesday. The officials say two of the Americans managed to conceal themselves when the attack began and later escaped unharmed.

One U.S. citizen was found dead Friday by Algerian forces that had launched a raid on Thursday in an attempt to free the hostages, the officials said.

The deceased American was identified as Frederick Buttaccio, a U.S. official confirmed. Buttaccio's remains have been recovered from the plant and his family has been notified, the official said.

Al-Qaida-linked militants claimed Friday that they were holding two American hostages and would exchange them for two people being held in the United States — the blind sheik Omar Abdel Rahman, convicted in the 1993 bombing of the World Trade Center and Aafie Siddiqque a 40-year-old Pakistani neuroscientist and mother of three, who was convicted of attacking U.S. soldiers in Afghanistan.

That would appear to account for all five Americans thought to have been at the plant, one U.S. official said, if the militants are telling the truth.

On Friday, the Algerian military had launched a second raid on the multinational cabal of kidnappers — led by a one-eyed al-Qaida associate — who laid siege to the In Amenas gas plant on Wednesday, state TV reported.

The situation was fluid, but the U.S. said one thing was carved in stone: It would not be cutting any deals with the captors.

"The United States does not negotiate with terrorists," State Department spokeswoman Victoria Nuland said of reports the militants were seeking the release of Sheik Omar Abdel Rahman, who is serving a life term for the 1993 bombing of the World Trade Center, and Aafia Siddiqui, a Pakistani scientist convicted of trying to kill U.S. soldiers after being arrested in Afghanistan in 2008.

Nuland confirmed there were Americans still being held alive but did not say how many.

The official Algerian news service APS said a total of 132 foreign nationals were taken hostage, and 100 had been freed by midday Friday. It said more than 500 Algerians had also been rescued.

Citing a security source, APS said 12 hostages, including some Westerners, were killed when Algeria staged its first rescue raid on Thursday without consulting other countries in advance. Eighteen militants were killed, it reported.

McFaul family via Reuters

Belfast native Stephen McFaul (right) is pictured with his sons Dylan (left) and Jake in this family handout photo taken four years ago and made available Thursday.

NBC News could not confirm the figures. The French government confirmed one of its citizens had died, and its defense minister said in an interview on France 3 TV Saturday morning that he believed no more French nationals were being held at the plant.

One worker told Reuters that the hostage-takers were out for blood.

"The terrorists told us at the very start that they would not hurt Muslims but were only interested in the Christians and infidels," said the man, who gave his name as Abdelkader. "'We will kill them,' they said."

The brother of escapee Stephen McFaul said the hostages had their mouths taped and their necks draped with explosives. They were being trucked around the compound when the Algerian military hit the compound with explosives, he told Reuters.

"The truck my brother was in crashed and at that stage Stephen was able to make a break for his freedom," Brian McFaul said after speaking with his brother’s wife. "He presumed everyone else in the other trucks was killed."

A French catering employee who worked at the plant said he spent 40 hours hiding under a bed after the militants stormed in Wednesday with a spray of gunfire, only emerging when the soldiers arrived.

"I could see myself ending up in a wooden box," Alexandre Berceaux told Europe 1 radio.

One rescued hostage told Algerian TV that the ordeal was an "exciting episode" and he was "impressed" with the army.

"I feel sorry for anybody who has been hurt, but other than that, I quite enjoyed it," the man said.

Algerian TV via Reuters TV

A British escapee, interviewed by Algerian TV, says the Algerian army did a "fantastic job" with Thursday's rescue.

Another said he was "very, very relieved to be out."

"Obviously, we still don't really know what is happening back on the site, so as much as we are glad to be out, our thoughts are with colleagues who are still there at the moment," he said on Algerian TV.

The militants' attack on the plant, operated in part by BP, was reportedly masterminded by Mokhtar bel Mokhtar, an Algerian with ties to al-Qaida who specializes in lucrative kidnappings and smuggling, according to U.S. officials. He earned the nickname Mr. Marlboro for trafficking cigarettes.

The raiding jihadists were described as a motley crew by an escaped radio operator who told Reuters: "Some were clean, others were dirty, some with beards, others without, and among them a French national with sunglasses."

The Mauritanian news agency ANI reported the group was retaliating over French military action against Islamic incursions in neighboring Mali. But the French operation began just a week ago and the assault on the plant appeared to be long-planned.

On Friday, another possible motive emerged, as ANI said the militants put forth the offer of the prisoner swap.

The offer was not verified by NBC News, but an ANI editor told The Associated Press the kidnappers’ spokesman began calling Thursday with "sounds of war in the background" and "threatened to kill all the hostages if the Algerian forces tried to liberate them."

British Prime Minister David Cameron told the House of Commons in London that Algeria maintains it green-lighted Thursday’s rescue raid because hostages’ lives were in danger when it appeared the militants were trying to spirit them out of the compound.

Secretary of State Hillary Rodham Clinton said she spoke with the prime minister of Algeria on Friday and requested that the "utmost care" be taken to protect the hostages.

"This is an extremely dangerous situation," she said. "No one knows better than Algeria how ruthless these groups are."

Kari Huus, Catherine Chomiak and Courtney Kube of NBC News and The Associated Press and Reuters contributed to this report.